As bacteria for promoting the formation of ice, Pseudomonas syringae and Erwinia ananas have hitherto been well known. Also, among Xanthomonas campestris bacteria, those known are the following three strains: the strain obtained from the leaves of Florida citrus [Goto Masao et el., Nisshokubyo-Hou, 54, 196 (1988); and Minsavage G. V. & Stall R. E., (1986), Proc. 6th Int. Conf. Plant Path. Bact., 994-1004], X. campestris pv. translucens [Kim H. K., Orser C., Lindow S. E. and Sands D. C., Plant Disease, 71, 994-997 (1987)], and the strain obtained from tea buds (INAX) [Goto Masao et el., Nisshokubyo-Hou, 54, 189-197 (1988)].
However, among these ice nucleus-forming bacteria, Pseudomonas syringae which is utilized for practical use is known to have phytopathogenicity, so that it may adversely affect the environment when it is used for spraying to form artificial snow. On the other hand, bacteria having no such phytopathogenicity generally grow slowly and thus may not be suitable for production on an industrial scale. Additionally, bacteria which are negative with respect to tobacco hypersensitivity reaction [Phytopathology, 77, 611-615 (1987)] are generally free of phytopathogenicity.
It would therefore be extremely advantageous to the industry to discover a strain which is negative with respect to tobacco hypersensitivity reaction and yet can grow at a high rate.
An object of the present invention is to provide a new ice nucleus-forming bacterium which has the above advantages. Another object of the present invention is to provide a process for the cultivation of the new ice nucleus-forming bacterium. Still another object of the present invention is to provide an ice nucleus-forming substance containing the new ice nucleus-forming bacterium and further to develop uses thereof in various fields.